Means for and method of accurately regulating chronometric devices



y 6, 1954 c. CHILOWSKY 2,682,744

' MEANS FOR AND METHOD OF ACCURATELY REGULATING CHRONOMETRIC DEVICES Filed Dec. 9, 1950 3 Sheets-Sheet l Altar-new July 6, .1954 c. CHILOWSKY MEANS FOR AND METHOD OF ACCURATELY REGULATING CHRONOMETRIC DEVICES Filed Dec. 9, 1950 3 Sheets-Sheet 2 Illllllllllllllllllllfl.

Allorn e ys July 6, 1954 c. .CHILOWSKY 2,682,744 MEANS FOR AND METHOD OF ACCURATELY REGULATING CHRONOMETRIC DEVICES Filed Dec. 9, 1950 3 Sheets-Sheet 3 INVENTOR.

Y W B Alforrzeya Patented July 6, 1954 UNITED STATES P OFFICE MEANS FOR AND METHOD OF ACCURATELY REGULATING CHRONOMETRIC DEVICES This invention relates to a means for, and method of, accurately regulating chronometric devices such as watches and clocks.

An object of the invention is to provide for very accurate adjustments of such devices by simple means which can readily be adapted to use in connection with the presently existing mechanism.

A further object is to provide means for automatic compensation of temperature errors.

Another object is to provide adjusting means, part of which may be fully enclosed within a water-proof case and part of which remains outside of said case, without requiring physical connection between said parts through the wall of said case.

A further object is to provide certain improvements in the form, construction and arrangement of the several parts and in the steps of the method of operation, by which the above-mentioned and other objects may effectively be attained.

According to the invention, the timing is regulated by means of a magnetic force (preferably magnetic attraction) applied to a part of the watch balance, so as to influence very slightly its oscillation period. It is preferable that the bal ance itself and'its spring be non-magnetic, and that the case also be made of a non-magnetic metal, such as stainless steel, silver, gold, bronze or the like.

A suitably shaped piece of some appropriate magnetic matter, such as, for instance, iron, nickel, cobalt, or a magnetic alloy is set into the balance, preferably on its periphery.

It is proposed, however, to have thi piece made ofPermalloy or other alloys which have great permeability in weak magnetic fields. One or both poles of a permanent magnet are placed in proximity of the periphery of the balance in such a way that the inserted piece mentioned above moves within the magnets field and is subject to its power of attraction. The swinging period of the balance is thus accelerated. (It is also possible, theoretically, to slow down the movement of the balance by placing the magnet in an appropriate position.) The watch may be timed by changing either the intensity of the magnetic field, or its direction, or its spatial gradient.

This result can be more simply attained if the position of the magnet or of its poles in regard to the balance and to its inserted term-magnetic part is changed. But the same effect can be produced with greater advantage if the magnetic flux is varied by varying the magnetic resistance 12 Claims. (01. 58-108) K sued June 6, 1950.

2 or by partial short-circuiting of the magnetic flux.

This system has the following advantages:

1. It becomes possible to time the movement of the watch (for instance) by a simple operation from the outside, without opening the lid of the case. This is particularly advantageous in the case of water-proof watches, which are generally difiicult to open and close.

2. The timing scale can be larger and the timing becomes, therefore, easier and more accurate.

3. As explained above, a much higher degree of precision can be obtained by means of such an exterior timing.

An important feature of the invention, however, is to combine with the timing of the watchs movement a rigorous automatic compensation of temperature variations, thus eliminating irregularity of movement, due to changes of temperature. This result is obtained by introducing into the magnetic circuit a section of composite laminations having progressively varying Curie point temperatures as disclosed in another connection in applicants Patent No. 2,510,801, is-

This will cause automatic variations of the magnetic flux (and, therefore, of the force affecting the inserted Permalloy piece) depending on the variations of the surrounding temperature according to a predetermined curve.

The Permalloy insert may be replaced in certain cases by a permanent magnet.

The method and means described above is used to make relatively slight corrections and is extremely accurate. The time variations of modern permanent magnets that have been submitted to an appropriate aging treatment are insignificant. Moreover such variations would affect only the correction itself, and the possible error introduced by such variation would be equally insignificant-for practical purposes nonexistent.

The same procedure of timing and thermic compensation could be applied to any type of chrcnometric device: watch, desk or wall clock (with spring balances or pendulum), instrument timing trains, etc.

Since the angular amplitude of a spring balance in a watch or a clock is considerable and since it gradually decreases as the main spring unwinds, it would be inconvenient to have a ingle insert of magnetic matter (such as Permalloy) or even several inserts placed along the balance, because this would cause an acceleration of the watchs movement-either positive or negative which would not be constant but would depend on the amplitude of the balance at any given moment, that is to say, on the tension of the main spring of the watch.

In order that the magnetic force between a fixed point (such as the permanent magnet) and the balance could produce an acceleration of movement regulated at will or automatically regulated in function of temperature, the accelera tion must be independent of the amplitude of the balance. To achieve this result the magnetic force affecting the balance must be proportionate to the deviation of the balance from its position at rest. In other word-s the component of the magnetic force accelerating the balance and the much greater acceleration force of the balance spring follow the same law, that is to say the acceleration force must be proportionate to the deviation of the balance from its position at rest. Various more or less complex types of magnetic action can be used to achieve a magnetic acceleration force affecting the balance and obeying this law. The preferred and simplest arrangement consists in giving to the ferromagnetic ele ment of the balance the form of a cardioid surrounding the balance and moving in a fixed magnetic field of constant strength.

Practical embodiments of the invention are shown in the accompanying drawings, in which:

Fig, 1 represents, in side elevation, a balance wheel and accompanying magnet,

Fig. 2 represents an axial section taken on the line IIII of Fig. 1,

Fig. 3 represents an axial section (similar to Fig. 2) through a balance wheel and magnet, showing one form of counterbalance,

Fig. i represents, in side elevation, a balance wheel and magnet, showing another form of counterbalance,

Fig. 5 represents, in axial section and on an enlarged scale, a balancing screw,

Fig. 6 represents, partly in section, a watch case with parts other than the balance wheel, magnet and adjusting means omitted,

Fig. '7 represents an axial section through the watch case of Fig. 6, on the line VIIVII,

Fig. 8 represents a detail side elevation of a balance wheel having a modified form of adjusting ring,

Fig. 9 represents a detail section through a modified form of magnet,

Fig. 10 represents a detail elevation of another modified form of magnet,

Fig. 11 represents a side elevation of a balance wheel having graduated peripheral fins, associated with a magnet somewhat spaced therefrom,

Fig. 12 represents, in edgewise elevation, a modified form of balance wheel and associated magnet,

Figs, 13 and 14, represent side elevations of modified forms of balance Wheels, associated with magnets as in Figs. 11 and 12,

Fig. 15 represents, in flatwise section, a watch case with parts other than the balance wheel, magnet and adjusting means omitted,

Fig. 16 represents a modification of the arrangement shown in Fig. 15,

Figs. 17 to 24, inclusive, represent diagrammatically in side elevation various possible magnet arrangements,

Figs. a to 28a show typical magnet arrangements (as in Figs. 17 to 24) and Figs. 25b to 28b are curves showing graphically the nature of variation of the magnetic field in the air gap of the magnets shown in Figs. 25a to 28a, and

Fig. 29 represents, in axial section similar to Figs. 2, 3 and '7, a modified balance wheel and magnet arrangement.

A simple example of a balance wheel and magnet designed to operate in accordance with the electro-physical law referred to above, is shown in Figs. 1 and 2, wherein a balance wheel I, pivoted around the axis 2 and balanced by a hairspring (not shown) is provided with a thin peripheral ring 3, of Permalloy or the like, projecting in a radial plane from the rim of the wheel. The ring 3 is assumed to have its periphery defined by a kind of cardioid curve, the central vector radius (R) of which corresponds to the center of oscillation of the balance wheel. A magnet assembly, comprising the permanent magnet 4 and pole pieces 5, 6, is disposed adjacent the balance wheel in such a position that the mg 3 moves through the air gap between the upper ends of said pole pieces, penetrating the magnetic field in the gap at an extent depending on the width of the ring at each given point.

As shown in Fig. 1, the balance wheel is deviated from the position of rest by an angle a, being the angle between the central radius R and the vector radius p passing through the middle of the section s of the ring which is within the magnetic field. Then the couple M of the magnetic action on the balance is i i M K do wherein K is a constant. In order to achieve the desired result and establish a relation of proportion between this magnetic force and the angle of deviation, it is necessary that M=aa, wherein a is constant. This result can be obtained by forming the periphery of the ring 3 as a curve (cardioid) resulting from the equation p=A-Bcc wherein A and B are constants.

The eccentric distribution of the total mass of the balance wheel I and ring 3 may be corrected by the provision of a balancing screw 1, preferably, like the balance wheel itself, of nonmagnetic material. The ring 3 could be replaced by a heart-shaped disc, of the same peripheral form; either the ring or the disc makes it possible to correct the rate of oscillation of the balance wheel quite independently from the amplitude of the oscillations.

However, in view of the very slight corrections with which this invention is concerned, the use of an accurately calculated cardioid ring or disc may generally be dispensed with in favor of a simple circular disc eccentrically mounted on the balance wheel in such a way as to approximate the cardioid ring or disc. Such an arrangement is shown in Fig. 3, wherein the balance wheel 8 is provided, on one side, with an eccentrically mounted annulus 9 (of Permalloy or the like) and on the other side with an annulus IQ, of non-magnetic material, eccentrically mounted in the opposite direction in order to counterbalance the annulus 9. The assembly of a permanent magnet II, with pole pieces I2, I3 is similar to the assembly 4, 5, 6 and is so placed that the annulus 9 projects into the gap between the pole pieces; the extent to which it is subjected to the magnetic field at that point varying as the balance wheel oscillates around its axis.

It is also possible to use a composite disc or ring, as. indicated in Fig. 4, comprising an inner part 14 of magnetic material and a complementary outer part I5 of non-magnetic material, such that the two parts together are mechanically symmetrical with respect tothe axis 16 of the balance wheel. The magnetic part 14 may be of cardioid shape, if desired, and the nonmagnetic part will be shaped as its complement in order to maintain perfect balance.

As an alternative, the magnetic material may be applied to the balance wheel in the form of the timing screws normally mounted in the rim of such a wheel. In Fig. 5 is shown a screw ll having a non-magnetic core l8 and a cylindrical shell I9 of magnetic material the relative radial proportions of the parts I8, l9 being varied in individual screws according to their position on the balance wheel. When properly disposed around the wheel (for instance, as shown in Fig. 13) a series of such screws will constitute a sort of discontinuous cardioid. The screws may be replaced by a series of small bars of magnetic material having varying dimensions (or varying magnetic-material content) disposed around the balance wheel so as to meet the requirement of the law of operation set forth above, i. e., that the couple must be approximately proportionate to the deviation from the position of rest.

If the cardioid (or its equivalent) is so disposed that the greatest amount of magnetic material is subjected to the strongest magnetic field when the balance wheel is at rest, then the acceleration due to the magnetic field will be positive, and the balance wheel will oscillate constantly at a more rapid rate than it would if the magnet were absent. Conversely, if the cardioid is reversed the magnetic acceleration is negative, and such an arrangement is perfectly correct.

The foregoing description constitutes a dis closure of the general principle, but without means for efiecting adjustments of the oscillation-modifying couple. It is evident that such adjustments can be made by varying, in some suitable manner, the effective intensity of the magnetic field. Means for varying, at will, the magnetic field are shown in Figs. 6 and 7, wherein the watch case 20 contains a non-magnetic inner shell 21 (water-tight, if desired), within which is mounted a balance wheel 22. The wheel 22 is shown as being of the type shown in Fig. l, but the wheels of Figs. 1, 3, 8, and the like could obviously be substituted. A permanent magnet 23 is located outside of the shell 2| and pole pieces 24, 24' extend inward of the shell from points opposite the poles of the magnet to form a gap through which moves the disc or ring 22 of the balance wheel. A curved blade 25 of magnetic material. tapering in thickness and/0r width is mounted on a slide 26 having a projecta ing finger-piece 21, the blade serving to shortcirouit partially the flux of the magnet against which it rests. As parts of the blade having a greater or less cross-section are brought into contact with the magnet (by moving the slide 26) the intensity of the magnetic field between the pole pieces 24, 24' is decreased or increased and the rate of oscillation of the balance wheel is varied correspondingly.

The blade 25 is elongated and its cross-section changes progressively, according to an appropriate curve, due to tapering in width or thickness or both, so that very precise and gradual corrections can be made in the effective intensity of the magnetic field, and, hence, in the rate of movement of the watch. A scale may be provided on the watch case adjacent the slot 20 through which the finger-piece 21 is operated, as an aid in obtaining accurate adjustments.

The mechanical forces which are affected in this type of adjustment are so small that relatively weak magnetic fields and small masses of magnetic material may be used successfully, while any possible formation of eddy currents or hysteresis may be disregarded. If necessary, however, the magnetic material may be subdivided, in a customary manner, as by fine radial cuts 28 (Fig. 8) or by forming the discs or rings of agglomerated ferro-magnetic powders or of materials having inherently low hysteresis characteristics.

In Fig. 9 is shown a modified detail of the magnet mounting wherein plugs of magnetic material 29, 29 are set into the shell 2| between the ends of the magnet 23 and the pole pieces 24, 24', in order to provide an uninterrupted magnetic armature. This arrangement is particularly desirable in cases where the shell may be too thick to permit eificient magnetization in the gap between the pole pieces if the flux is interrupted at two additional points, as in Fig. 7.

Fig. 10 shows a detail modification in which the intensity of the magnetic field is varied by forming a gap between the magnet 30 and one of the pole pieces 3!, and by moving through this gap a blade 32 of varying thickness (corresponding to some extent to the blade 25 and operated in a similar manner); as thicker parts of the blade enter the gap the resistance of the magnetic circuit is lowered and the intensity of the field between the ends of the pole pieces is increased.

In the magnetic couplings thus far described the magnetic material element (or elements) on the balance wheel moves within the air gap of a permanent magnet or of the magnetic armature, the magnetic field in the gap being parallel to the axis of the balance wheel. This parallel arrangement gives accurate results in a simple manner, but it is also possible to use a magnetic field perpendicular to the axis of the balance wheel, or to place the permanent magnet outside the watch case and at a suitable distance from the magnetic elements on the wheel. Thus Figs. 11, 12, 13 and 14. illustrate couplings in which the magnetic elements are spaced a certain distance from each other, and Figs. 15 and 16 show couplings in which the magnetic field is perpendicular to the axis of the balance wheel.

Fig. 11 represents a magnetic coupling in which the balance wheel 33 is provided with radiating peripheral fins 3 3 of magnetic material and of progressively varying size, constituting a kind of discontinuous cardioid, the resulting mechanical unbalance being corrected by the provision of a suitable non-magnetic mass 35. The permanent magnet 35 is spaced from the balance wheel and lies parallel to the axis 3'! thereof; the magnet may be mounted at the periphery of the watch shell and the effective intensity of its field may be regulated by means similar to that shown in Figs. 6 and 7, which will be operative whether the magnet is inside or outside of the shell. (It is assumed in this case that the magnet will be inside, the short-circuiting blade will be outside and the wall of the shell at that point will be relatively thin.)

In Fig. 12 the magnetic material is in the form of rods or pins 38 set into the rim 39 of the balance wheel. If the rods or pins are of equal size and symmetrical distribution, but containing progressively varying proportions of magnetic material, no counterbalancing is needed. The magnet may be disposed, and its field regulated, as described in connection with Fig. 11.

Fig. 13 shows a simplified and less accurate form of magnetic coupling, in which the balance wheel 4! is provided with a plurality of timing screws, only one of which, 42, is of magnetic material. The magnet 43 is disposed, and operates, as described above.

According to Fig. 14 a small permanent magnet 44 is mounted on the rim of the balance wheel, lying parallel to its axis, and counterbalanced by the mass 45. The separate magnet 46 (corresponding to 36, 4B and 43 in Figs. 11, 12 and 13) should be placed so that its N. and S. poles are opposite, respectively, the S. and N. poles of magnet 14. Either of the magnets M, 46 may be replaced by a bar of magnetic material.

Figs. 15 and 16 show, diagrammatically, arrangements in which the permanent magnet, with its armature or armatures, is substantially annular and lies in a suitably shaped recess around the periphery of the watch. If the watch case is not round, the shape of the magnet assembly can be modified accordingly.

In Fig. 15 the magnet 4'1 is provided with armatures 48, it, forming together a complete annulus except for the air gap t, located at the point nearest the balance wheel 5!. The latter carries, in a simplified arrangement, a small mass of magnetic material (counterbalanced, if desired) Which is drawn toward the gap 50 by the diffused magnetic field surrounding said gap. The elfective intensity of this field is varied by shifting peripherally across the gap a blade 53 of magnetic material, moved by means of the finger piece 54 which is accessible through a slot in the edge of the watch case; the blade 53 has a progressively varyingcross-section, as in the case of the blade 25 (Figs. 6 and 7) so that the extent of short-circuiting of the field can be varied.

In the alternative arrangement of Fig. 16 there are gaps 55, 55 at each end of the magnet 51, between said magnet and the ends of a single lon armature 53; the mass of magnetic material 58 on the balance wheel is attracted by the field around the 55 and the intensity of this field is varied according to the position of an adjustable short-circuiting blade 6!! (similar to blade 53) lying across the gap 55. The magnetic pieces 42, A l, 52 and 59 are so located that the magnetic couple is zero at rest position of the balance.

The magnetic action described above is not only convenient method of timing a waterproof watch, by means of a very simple manipulation of an outside button, but also renders the movement much more precise both in the cases of waterproef and. of non-waterproof watches. To insure this accuracy, the owner of the watch will follow the simple rule of slightly moving the regulating button or finger-piece at the time when he checks the watch and sets the hands, which inevitably has to be done at not too long intervals. He will thus regulate the movement, speeding it up if the watch is slow and slowing it down if it is fast. If such a timing takes place, for instance, once a week and if the owner of the watch takes care to rectify each time the too fast or too slow movement of the watch, by moving the button as indicated on the scale on the rim of the watch, the watch will automatically become more accurate and the checking periods can be lengthened. This concerns especially the watches of average precision. The simple gesture of automatic movement regulation (in itself much more simple than the seting of the watch hands) compensates and eliminates automatically the errors of movement pro- 8 g duced by various uncontrollable and often con tradictory outside factors, such as variations of outside temperatures, vertical or horizontal position of the watch, vibrations or shocks, etc. Inexactitudes of movement caused by the environment and by the manner of handling the watch of its individual owner will be thus automatically eliminated and a kind of adaptation of the watch to its environment will take place.

As an aid in assuring the adjustment of the watch movement at suitable desired intervals (particularly, intervals of more than one day) the watch may be provided with a supplementary hour and day measuring device, showing clearly the time elapsed since the last adjustment.

The use of magnetic coupling of action does more than facilitate the timing of waterproof watches and increase the accuracy of all kinds of watches; its other and principal object is the automatic and usually complete compensation of influence of temperature on clock movement and the consequent elimination of temperature errors.

For this purpose it is proposed to combine the magnetic coupling described above, which permits regulating the watch movement by varying the magnetic field, with the general procedure of thermic compensation. (See Pat. No. 2,501,801 mentioned above.)

According to this compensation procedure, magnetic action is established affecting the moving part of an apparatus and into the field of this magnetic action a special magnetic body is introduced. This body is constituted by a series of ferromagnetic alloys, the composition and Curie point of which vary progressively within suitable limits of temperature. It thus becomes possible to obtain an automatic variation of this magnetic action which will depend on the surrounding temperature of the magetic field and on the mechanical force of the magnetic action.

By varying within the body the proportion and the distribution of elements of different Curie points, it is possible to obtain any desired law of variation of the magnetic field depending on surrounding temperature and thus to obtain any desired law to correct thermic errors.

It is preferable to use for such composite bodies certain ferromagnetic alloys and specially nickel alloys with a small proportion of non-magnetic metals such as, for instance, aluminum, chromium, molybdenum, copper, silicon, etc., the Curie temperatures of which lie within the limits of surrounding temperatures. The Curie temperature of such an alloy decreases progressively with the increase of the percentage of non-magnetic metal.

These elements or composite sections are formed, for instance, by an assemblage of laminations or other magnetic elements having progressively varying Curie point temperatures within perscribed temperature limits.

Thse elements can also be constituted by mixing in various proportions a certain number of powdered alloys having Curie points that vary progressively within set limits.

When introducing such sets of laminations or agglomerated powders into the magnetic coupling described above, it becomes possible to eliminate automatically and completely the temperature errors of a watch, whatever its curve may be.

These composite laminations or composite powder elements function as follows: In a set or series of juxtaposed composite laminations with rogressively varying Curie point temperatures the phenomenon occurs that, when the ambient temperature reaches the Curie point temperature of a given lamina, this lamina loses its magnetic property and becomes nonmagnetic, and its magnetic permeability disappears. So, with the rise of ambient temperature more and more lamintaionsbecome nonmagnetic. If these lamintaions are short-circuiting the magnetic flux of the permanent magnet, the working field of the magnet increases with the temperature. On the contrary, if the laminations are in series with the magnetic flux, the working magnetic field decreases.

The same phenomenon occurs in the case of composite powders, e. g., a homogeneous mixture of powders of alloys with difierent Curie point temperatures. At low temperature all the grains of the agglomerated mixture have a definite magnetic permeability. With the rise of ambient temperature, more and more grains become non-magnetic and the powder body becomes less permeable, until a final disappearance of all permeability. By varying the relative proportion of powders of difierent alloys one can obtain any desired curve of change of permeability with the temperature, and any curve of variation of the working magnetic field in function of the ambient temperature.

It should be noted that the invention forsees a more or less partial compensation of the temperature errors of a watch through the use, in the above magnetic coupling, of certain special ferromagnetic alloys such as Thermoperm, Isoperm, Calmalloy, etc., which are being used for thermic compensation of electric meters with permanent magnet and moving coils. But such a compensation cannot be complete.

Figs. 17 to 24, inclusive, represent diagrammatically various arrangements of -composite sections combined with magnets and their armatures in order to compensate for temperature changes according to corresponding curves. In each case it is assumed that the magnet assembly is to be used with a balance wheel as shown in Figs. 1 to 8, although certain of the magnet assemblies are also obviously useful in the arrangements of Figs. and 16, and in any case with or without adjustable short-circuiting means. (See also Fig. 29, described below.)

In Fig. 17 the permanent magnet 6! is provided with pole pieces 62, 62' forming an air gap 63. Across the poles of the magnet there is inserted a composite section 64 comprising a series of ferromagnetic alloy laminations having Curie points which vary progressively from end to end of the series, the laminations being disposed perpendicular to the magnetic flux in order to impose on the field in the gap 63 certain desired characteristics of variations as a function of changes of temperature. That is, the magnetic fiux is short-circuited to extents varying with the changes in permeability of the composite section under the influence of temperature changes, according to a predetermined curve. A suitable choice of Curie temperature range for the series of laminations, and of their grouping, makes possible any desirable variation in their response to temperature changes in terms of permeability.

The parts shown in Fig. 18 bear the same general relationship as in Fig. 17, except that the series of laminations having progressively varied Curie points (composite section 65) is dis- 10 posed so that the laminations lie parallel to the magnetic flux and thus have a difierent characteristic curve.

In Fig. 19, separate composite sections 66, 66' are interposed between the ends of the magnet 67 and the pole pieces 68, 68', the laminations in each section lying parallel to the flux. The arrangement shown in Fig. 20 is similar, but the laminations in section 69 lie perpendicular to the flux while the laminations in section 69' lie parallel to the flux.

In Fig. 21 a double composite section is used in short-circuiting position (as in Figsjl'i' and 18), one part "Hi having its laminations perpendicular, and the other part 10' having its laminations parallel, to the flux and said parts being assembled in series. In the double composite section of Fig. 22 the part H having its laminations parallel, and the part I i having its laminations perpendicular, to the flux are assembled in parallel in short-circuiting position.

Figs. 23 and 24 represent, respectively, important modifications of Fig. 17 or 18 and of Fig. 19 or 20, in which the composite section 12 or sections 13, 13' are formed of a suitable compact, generally agglomerated, mixture of powder of ferromagnetic alloys having different Curie points in suitable proportions. The variation of Curie points may be in a progressive series or otherwise, and the mixture should be homogeneous, so that heating the agglomerated mixture to the temperature of one or more of the said Curie points will cause a decrease in its permeability as a function of the proportion of the mixture whose Curie point is reached or exceeded. Due to the great flexibility in choice and proportions of the mixture of powders of alloys with different Curie points, and in the distribution of materials the section can be made to have any desired characteristic curve of response. Since it is now possible to determine very rapidly and accurately the curve representing variations in operation of a watch movement in function of temperature, it will be possible to introduce into the magnetic coupling a composite section (or sections) of agglomerated powder which will compensate exactly the established curve of thermic errors and will completely eliminate such errors.

It is well known that any ferromagnetic alloy, and therefore any composite section of laminations or composite agglomeration of the character described above, will show a permeability curve that will always decrease in function of temperature, up to the highest Curie point-of the components. However, it is possible to obtain any type of curve of the magnetic field variations by inserting the above mentioned laminations or powder agglomerations into the magnetic circuit in series with the air gap, or setting them up parallel to the air gap, or by a combined parallel and serial set-up. This is illustrated in Figs. 25 to 28.

Thus the simple short-cirouiting of the magnet represented in Fig. 25a (corresponding basically to Figs. 17, 18, 21, 22 and 23) gives the curve of Fig. 2512, showing the intensity of the magnetic field increasing with the temperature.

A magnet with a series -arrangement represented in Fig. 26a (corresponding basically to Figs. 19, 20 and 24) gives the curve of Fig. 26?) showing the intensity of the magnetic field decreasing in function of temperature.

The combined arrangements of serial and parallel agglomerations, representing in Figs, 27a and 28a can give, either of them, the curves shown in Figs. 27!) and 28b of variations of the utilized magnetic field. These curves will have both increasing and decreasing sections and will thus indicate maximum and minimum points, depending on whether or not, and at what temperature, the variation of the permeability of the shortcircuiting elements prevails over that of the serial elements.

For instance, in Fig. 27a, the agglomeration 15 (parallel with the magnet) has a rapid variation of permeability in the case of temperature lower than the variation temperature of the elements 16, H6 (in series). The variation curve of the magnetic field indicates, therefore, first an increase and then a decrease.

The inverse will take place in the case indicated in Fig. 28a.

The curve of temperature errors can have different forms. In the case of a spring made of Elinvar, for instance, the clock movement is retarded in function of temperature increase and curves of the type represented in Figs. 25a and 2517 will compensate the thermic error of the watch or clock movement.

In the rather frequent case of a bi-metallic balance and an ordinary spring the curve of a compensated watch shows a maximum of speed at an average temperature and retardations at both extreme temperatures. arrangement of magnets indicated in Fig. 28a should be used, which gives curves (Fig. 28b) corresponding to the variations of the magnetic field in function of temperature.

In order to realize thermic compensation it is preferable to use systems with a magnetic field that varies greatly in function of temperature. The magnetic field and the forces applied should, however, be weak, so as to interfere as little as possible with the normal functioning of the watch and to produce only the necessary corrections.

This thermic compensation, obtained by the introduction of a composite body into the magnetic coupling of the balance with progressively varying Curie point temperatures, can be applied quite independently from the timing procedure described above and which is regulated from the outside without opening the lid. If necessary the entire arrangement of thermic compensation by means of magnetic coupling can be placed within the watch; or the fixed parts of the magnetic coupling can be placed on the lid or case of the watch, or between the lid or case and the mechanism of the watch.

The invention also proposesand especially for chain and wrist watches-a very simple combination of the two methods described above: the one of magnetic timing of the movement from the outside and the one of complete magnetic compensation of thermic errors.

Fig. 29 illustrates diagrammatically such a combination. In a mechanism comprising a permanent magnet '11 and a system of thermic compensation l8, eliminating thermic errors, the field of the permanent magnet is slightly short-circuited by a movable ferromagnetic blade T9 (of soft iron, Permalloy, or the like) of varying thickness, similar to the blades 25, 53 or 60. The shifting of the blade 19 by means of the finger piece 8!] permits varying slightly and at will the magnetic field of the coupling and thus accelerating or slowing down the movement of the watch. Such a variation of the magnetic field can be obtained, as was explained above, through the water-tight shell of the watch case. The in- In such a case the vention can be applied to any watch or clock with a spring. The application of the same procedure to any kind of clock or clock movement actuated by weights is also contemplated.

It is also provided that, in order to obtain an automatic compensation of temperature errors of a time measuring device, the composite laminations or composite powder elements can be intro duced in the mobile part of the ferromagnetic coupling. So, for instance, the cardioid element fixed on the balance wheel can be made of agglomerated composite powders. Evidently, a reversed disposition can also be used.

In the case of a pendulum clock, a disc-shaped eccentric element can be set into the lower end of the pendulum which will move in the air gap of a magnet equipped with the compensation device described above. However, since the amplitude of the pendulum remains constant, it is possible to use various, more simple magnetic couplings, for instance a piece of magnetic matter (such as Permalloy or soft iron) and a permanent magnet, the exterior magnetic field of which is suitably compensated in function of the temperature as disclosed above, and following the curve of thermic errors characteristic of the given clock. Either the permanent magnet, or the piece of magnetic material can constitute the immovable part of the magnetic coupling. It can also be constituted by two permanent magnets (of linear or horseshoe-shape) equipped with a thermic compensation device which corresponds to the curve of thermic errors of the clock. One of r the magnets is static, the other mobile, the latter being fixed to the pendulum, preferably at its extremity.

With the presently available materials, this procedure allows compensation for any error due to environing temperature down to -45 C. This result is obtained, for instance, by using an agglomerate containing a mixture of powders of a series of nickel-silicon alloys containing variable small percentages of silicon (from 0 to 6%). Such a procedure is important for time-pieces used at high altitude on airplanes.

The thermic compensation procedure described above can be applied to watches and clocks in which temperature errors have already been partially corrected and reduced to the minimum by means of existing techniques. In such cases the present procedure corrects only a relatively small but pertinent remaining error, which cannot be dealt with otherwise. This is important for all relatively high-precision Watches, of the type of good pocket watches, wrist watches, etc. This has a special importance for precision watches and clocks, naval and astronomic time-pieces, etc.

The procedure can also be applied-and this is especially important-to watches and clocks that have not yet been submitted to the fine adjustments of the pendulum and of the spring balance, or to the timing and control of movement in function of temperature, which insure at present the relatively great independence and accuracy of movement of a good watch. The present invention will render such adjustments unnecessary.

The magnetic compensation procedure described above will eliminate all thermic errors in a simple, rudimentary and inexpensive watch which has no thermic compensation device. This result will be attained by introducing into the above described magnetic coupling a capsule of agglomerated powder bearing a definite number corresponding to the desired curve of permeability variations in function of temperature.

It will bepossible, in the case of such a magnetically compensated (magnetic) watch to do without all the expenses and efforts involved in the mechanical compensation used in present techniques. The expenses involved in the assiduous work of timing and controlling which render the modern watches accurate and which often represent a considerable part of the cost-price can also be avoided.

What I claim is:

1. In time measuring, the method of varying the oscillation period of an oscillating element having a natural frequency of mechanical oscillation which comprises, subjecting said element to the action of a magnetic couple between a ferromagnetic body attached to said element in a position to oscillate therewith and a second relatively fixed ferromagnetic body, and varying the intensity of the magnetic couple automatically as a function of temperature, whereby the degree of variation of the oscillation period is adjusted in such a way as to compensate and correct thermally caused aberrations from the desired frequency of oscillation.

2. The method according to claim 1 in which the intensity of the magnetic couple is also varied by short-circuiting to a desired extent the magnetic flux originating from a permanent magnet.

3. The method according to claim 1 in which the oscillating element has an amplitude of oscillation varying with time, and in which the magnetic couple is at each moment proportional to the momentary angular deviation of the oscillating element from its position of rest.

4. Means for varying the oscillation period of an oscillating element having a natural frequency of mechanical oscillation comprising, a spring balance mounted for oscillation about a fixed axis and having an amplitude of oscillation varying with time, ferromagnetic material having approximately the peripheral outline of a card-ioid with the axis of said balance as its axis and being attached to said balance in a position to oscillate therewith and a body of ferromagnetic material separately mounted adjacent said element, at least part of said ferromagnetic material being a permanent magnet.

5. Means according to claim 4 in which the material attached to the element is subdivided radially into separate peripheral parts.

6. Means according to claim 4 which includes a movable ferromagnetic member and means for moving said member to different adjusted positions in' the magnetic field of said magnet for adjustably short-circuiting the magnetic flux.

Number 7. Means according to claim 4 in which the said separately mounted body includes a permanent magnet and at least one armature, and which includes a movable ferromagnetic member and means for moving said member to different adjusted positions in the magnetic field of said magnet for adjustably short-circuiting the magnetic flux.

8. Means for varying the oscillation period of an oscillating element having a natural frequency of mechanical oscillation in a time-measuring device comprising, an element mounted for oscillation about a fixed axis, ferromagnetic material attached to said element in a position to oscillate therewith, means including a permanent magnet separately mounted adjacent said element for creating a magnetic field in a position to affect said element and influence itsoscillation period, and at least one composite section of ferromagnetic material disposed in the magnetic circuit with said magnet, said section including materials which, in different parts, have progres sively different Curie points, said points being selected and said parts being disposed so as to produce a curve of variation of magnetic force in function of temperature adapted to compensate the curve of thermal errors of said timemeasuring device.

9. Means according to claim 8 in which at least one composite section is disposed in series with said magnet and with said magnetic field.

10. Means according to claim 8 in which at least one composite section is disposed in parallel with said magnet.

11. Means according to claim 8 in which at least one composite section is disposed in series with said magnet and said magnetic field and in which at least one composite section is disposed in parallel with said magnet.

12. Means according to claim 8 which includes a movable ferromagnetic member and means for moving said member to different adjusted positions in the magnetic field of said magnet for adjustably short-circuiting the magnetic flux.

References Cited in the file of this patent,

UNITED STATES PATENTS Name Date 1,517,008 Jones Nov. 25, 1924 1,706,171 Kinnard Mar. 19, 1929 1,812,740 Ehlers June 30, 1931 1,982,689 Polydorofi Dec. 4, 1934 1,997,193 Kato et al Apr. 9, 1935 2,313,466 Dicke Mar. 9, 1943 FOREIGN PATENTS Number Country Date 14,004 Switzerland Jan. 30, 1897 

